The invention is directed to improvements in fuel injection pumps for internal combustion engines.
A fuel injection pump of this type that is known from European Patent Publication EP-A-0039304 is designed in the manner of a distributor injection pump, in that radially disposed pump pistons are provided in a rotatingly driven distributor that are supported via roller shoes on a cam race disposed on an annular element that is essentially stationarily or rotatably seated in the pump housing. By means of the inwardly pointing cams, the pump pistons experience a back-and-forth motion, whereby intake and pumping cycles alternate, and fuel is thus supplied at high pressure to one of a plurality of individual injection lines, depending on the positions of the distributor. To adjust the point in time during which a respective high-pressure pumping cycle begins, the cam ring is rotatably disposed. For this purpose, it has a radially screwed-in connecting element whose outer end is a ball end, with which it engages an adjusting piston of an injection timing mechanism. In the process the adjusting piston is displaced by a hydraulic control fluid counter to the force of a restoring spring, and thus changes the position of rotation of the cam ring and therefore the beginning of high-pressure pumping of the pump piston or the start of fuel injection.
In the known embodiment the connecting member is therefore screwed into a tapped bore disposed in a radial cam ring. Such a bore is disadvantageous for a very high-stressed part like the cam ring, which must be hardened to have the required wear-resistance in operation on the one hand, yet because of this hardening is extremely notch-sensitive on the other. Added to this are the costs of cutting the tapped bore and the screw connection of the connecting member.